Percent problem

The length of one side of a square is increased by 25%. By what percent would the length of the adjacent side have to be decreased so that the area of the new figure (which will be rectangular) is the same as the area of the original square?

If something is increased by 25%, you're taking a number and adding 25% of it. Say the number is 40. If you're increasing 40 by 25%, you take 25% of 40, which is 10 (0.25 * 40 = 10), and add it to 40 to get 50. In other words, 40 + 10 = 50.

Now, if you take a number x and increase it by 25%, do the same thing. 25% of x = 0.25x, and add it to the number: x + 0.25x, or 1.25x. Does that help?